1. Field of the Invention
The present invention generally relates to element handling systems and, in particular, to a system and method for transmitting power and control signals to an element retrieval device.
2. Related Art
Cartridge handling systems transport movable data cartridges stored within a cartridge storage library, to various locations within the cartridge handling system in response to commands received from a host computer. Moreover, when the host computer is to read from and/or write to a data cartridge, the host computer may issue a command for retrieving the data cartridge and loading the data cartridge into a cartridge interface device accessible to the host computer.
For example, a cartridge handling system may employ a cartridge retrieval device that locates and retrieves the requested data cartridge from the cartridge storage library. The cartridge retrieval device normally comprises a “picker” for grabbing the requested data cartridge and removing the data cartridge from the cartridge storage library. After utilizing the picker to retrieve the requested data cartridge, the cartridge retrieval device transports the cartridge to the cartridge interface device and again utilizes the picker to load the cartridge into the cartridge interface device. The host computer then utilizes the cartridge interface device to read from and/or write to the loaded data cartridge. Once the host computer no longer needs access to the data cartridge, the host computer issues a command for returning the data cartridge to the cartridge storage library. In response to such a command, the cartridge retrieval device retrieves the cartridge from the cartridge interface device and transports the cartridge back to the cartridge storage library.
Control signals for instructing a cartridge retrieval device to retrieve and move cartridges, as described above, and/or a power signal for providing the cartridge retrieval device with power are typically transmitted to the cartridge retrieval device via one or more wires coupled to the cartridge retrieval device. As the cartridge retrieval device moves from one location to another and/or handles data cartridges, the foregoing wires can become entangled with the cartridge retrieval device causing the cartridge retrieval device to malfunction. Further, such wires are typically flexed or bent when the cartridge retrieval device moves, thereby causing the wires to fatigue and eventually fail.
In an effort to prevent such problems, the aforementioned power and control wires are sometimes eliminated from the design of the cartridge handling system. The power wires may be eliminated by installing a battery on the cartridge retrieval device or by transmitting a power signal to the cartridge retrieval device over conductive track members that may also be used to guide the cartridge retrieval device. Further the control wires may be eliminated by wirelessly transmitting the control signals to the cartridge retrieval device. For example, U.S. Pat. No. 5,303,214 discloses the use of infrared signals to communicate the control signals to a wireless receiver residing on the cartridge retrieval device. However, as the cartridge retrieval device moves, ensuring that such a wireless receiver is correctly positioned for receiving the wireless control signals may be problematic, particularly for cartridge retrieval devices capable of moving in at least two dimensions.